Lotus Elan and Lotus Elan Plus 2 Forums

Put a block on the engine stand to build a new race engine for the Elan. Aiming to have it complete for my next race in early November.

General specs:
1600 cc standard stroke 83.5mm bore 120E block
11.5:1 compression ratio and premium unleaded 98 RON fuel ( Avgas is being banned in historic racing here )
Carrillo rods, JE pistons, Datsum L16 crank , 8500 rpm rev limited but good for over 9k+
McCoy Stage 4 converted head 1.625 and 1.4 inch valves with QED race springs( red) and Tony Ingram titanium retainers ( I like to mix and match )
McCoy .460 lift 300 degree inlet .450 lift 290 degree exhaust cams
45DCOEs with 36 mm chokes and TTR race headers
Swinging baffle wet sump to my own design with HV / HP pump
Bosch points based distributor, magnecor leads and NGK BP8ES plugs
small diameter crank pulley
shortened jackshaft
lightweight steel flywheel ( I have an alloy one but not sure if I want to try it on this engine)
I was looking to use a new modular water pump front cover but no one has them currently so may need to rebuild and fit one of the spares I have.


I expect around 180hp at flywheel at around 7500 to 8500 rpm with a nice fat torque curve



I will post some more photos as i go.

cheers
Rohan

I look forward to following this thread, Rohan.

Best of luck!

Tim

trw99 wrote:I look forward to following this thread, Rohan.

Best of luck!

Tim

likewise !

esp. head work and valves setup and clearances - also interested in the Datsun crank (though I would not try it myself)...

Nice build spec! Looks like you already have a couple of extra Engines in the background.......what are those for?

Hi Rohan
I have a few questions about how some of your mods would work on a street engine.

1) What is the reasoning/advantage of using 45DCOE's vs. 40 DCOE's if using 36mm chokes in each?
2) Would shortening the jackshaft and using a light steel flywheel be a worthwhile road modification?
Good luck with the build!

Thanks,
Chris

rgh0 wrote:

I expect around 180hp at flywheel at around 7500 to 8500 rpm with a nice fat torque curve


cheers
Rohan

Not as flat as this one! the engine cost me ?850



Seriously, I look forward to seeing your build, always very informative and interesting to read your posts Rohan!

As a matter of interest how are the Datsun 1600 crank conversions holding up in the longer term? Last I spoke to Lotusmarques who were promoting them at one stage was that they were "no longer a fan" although I could not get an answer as to why.

I know factory steel cranks have hardened journals. Does the machining of the crank to make it fit a Twin Cam destroy this hardening or is some kind of rehardening process applied to restore them to their original condition?

2cams70 wrote:As a matter of interest how are the Datsun 1600 crank conversions holding up in the longer term? Last I spoke to Lotusmarques who were promoting them at one stage was that they were "no longer a fan" although I could not get an answer as to why.

I know factory steel cranks have hardened journals. Does the machining of the crank to make it fit a Twin Cam destroy this hardening or is some kind of rehardening process applied to restore them to their original condition?

The cranks appear to be plenty hard enough after machining without surface treatment such as nitriding. I have never seen any significant wear in mine over the last 25 years. I know a large number of people who have used them without problem. I know of only one that has broken in racing and that was a friend who uses over 9000 rpm all the time in his S4 Seven chasing 3 litre Porches. Above 8500 rpm in a Twink the vibrations get really severe so anything and everything starts to break unless you rebuild very very frequently ( every 15 to 30 hours of running) and do lots of crack checking for every rebuild. I suspect Steve is no longer a fan as the L16 cranks are now hard to source locally so not much of a business in modifying them anymore and more money selling new billet cranks

Spyder fan wrote:

rgh0 wrote:

I expect around 180hp at flywheel at around 7500 to 8500 rpm with a nice fat torque curve


cheers
Rohan

Not as flat as this one! the engine cost me ?850



Seriously, I look forward to seeing your build, always very informative and interesting to read your posts Rohan!

HAHAHHA - but I cant run a Zetec in my historic category. But it is a nice demonstration that a modern 4 valve fuel injected engine is similar to a 50 year old twin cam in specific output

cheers
Rohan

seniorchristo wrote:Hi Rohan
I have a few questions about how some of your mods would work on a street engine.

1) What is the reasoning/advantage of using 45DCOE's vs. 40 DCOE's if using 36mm chokes in each?
2) Would shortening the jackshaft and using a light steel flywheel be a worthwhile road modification?
Good luck with the build!

Thanks,
Chris

HI Chris

1. 36 mm chokes are the largest you can use in a 40 DCOE and hard to tune due tto the small difference between the carb body and the choke. In a 45 its easier to tune. 45's also have some construction detail difference which make them a better race carb.

2. The lightened flywheel gives you a more responsive engine and if not using the mechanical fuel pump the shortened jackshaft reduces bearing losses so both will make an improvement in a road engine and worthwhile doing if your building a tuned road engine.

cheers
Rohan

Certified Lotus wrote:Nice build spec! Looks like you already have a couple of extra Engines in the background.......what are those for?

One is the race engine that I pulled from my Elan, I will rebuild that once I have the new engine in. The other is an engine for my Plus 2 that I have got ready to go in once I finish reassembling the body after its respray.

cheers
Rohan

nmauduit wrote:

trw99 wrote:I look forward to following this thread, Rohan.

Best of luck!

Tim

likewise !

esp. head work and valves setup and clearances - also interested in the Datsun crank (though I would not try it myself)...

As I work through the build I will give some more details. If you have specific questions on anything you see just ask and I will try to provide more information

cheers
Rohan

Interesting stuff on the crank, I, too, have an L18 crank waiting for machining. Probably a bit overkill for the
street.

Greg,

I have an L18 crank on the bench that will be used with a tall block for the S2. What flywheel will you be using?I had good luck home machining a Fidenza aluminum flywheel to work with my Zetec, mated to a 2000E and using a pre-engaged starter.

I'd be interested to know how these cranks compare vibration wise with a billet steel fully counterweighted crank.

The L16 Datsun is 4 counterweight (like the original)
The L18 Datsun is fully counterweighted
My understanding is that the L18 crank can only be used with the 1.6L kent block, not the 1.5L/twin cam block

With all the machining that goes on with these Nissan cranks to make them fit what is the weight balance like with each individual counterweight? Perhaps even though the whole crank can be balanced OK if each individual counterweight is significantly different in weight this will lead to flexure of the crankshaft and hence vibration at high RPM?. On the balancing machine you can't spin it to 9,000RPM.

Surely fully counterweighted cranks are best for high RPM?